Honeydew Deposition by the Giant Willow Aphid (Tuberolachnus salignus) Affects Soil Biota and Soil Biochemical Properties

Abstract

Infestation of willow plants by the giant willow aphid Tuberolachnus salignus (Hemiptera: Aphididae) is associated with copious deposition of sugar-rich honeydew under the plant canopy. We explored the effect of aphid honeydew on the soil biota and biochemical indicators in a two-year field trial. Soil samples from under aphid-infested and control willow trees, as well as samples from black sooty mould spots under the aphid-infested willows were compared; soil samples before aphid inoculation were used as a baseline. The honeydew deposition had a positive effect on the total soil carbon (C), but not on the total soil nitrogen content or soil pH. Microbial biomass C, basal respiration, number of yeast colony forming units, and the geometric mean of activities for six enzymes were significantly higher in honeydew-affected soils than in the control treatment on both years. The honeydew deposition also increased soil meso-fauna abundance, especially in the black sooty mould spots. The soil biochemical properties, which differed before and after aphid infestation, showed considerable overlap between the first and second year post-infestation. The results highlight the cascading effects of T. salignus on soil biological activity and the importance of using a multitrophic approach to explore similar scenarios.

Are invasive species promoting yellowjacket invasion in Patagonia?

“…Removal of invasive willows from stream and river margins could be beneficial, albeit expensive. Alternatives to this could involve managing GWA through semiochemicals (Tun et al., 2020) and biocontrol agents such as parasitoids (Bochniarz, 2020). Reducing GWA infestations would impact yellowjacket populations in situations where willow removal is not possible.…”

“…When found in high densities, the honeydew can accumulate on lower branches, foliage and ground where it can have numerous negative impacts. Some studies report that honeydew depositions can affect soil biota (Milcu et al., 2015; Tun et al., 2020) and can impact economic activities. In addition to reducing growth and survival rates of willows (Collins et al., 2001), honeybees that feed on GWA exudate produce lower‐quality honey because it crystallizes early due to its high melezitose content.…”

Seasonal abundance of Tuberolachnus salignus and its effect on flowering of host willows of varying susceptibility

“…The giant willow aphid deposits copious amounts of honeydew in the soil affecting soil biota and chemistry (Tun, Clavijo McCormick, Jones, Garbuz, et al., 2020), which in turn may influence resource availability. Therefore, T. salignus impacts on host–plant reproductive phenology may not only be direct through herbivory but also indirect through modification of soil properties.…”

A mini-review on the impact of common gorse in its introduced ranges

“…Invasive plants can provide shelter, reproductive or nesting sites, and alternative food sources for detritivores, pollinators, herbivores, and predators (Bowers et al 1992 ; Nagy et al 1998 ; Longcore 2003 ; Wonham et al 2005 ; Levin et al 2006 ; Effah et al 2020 ). Some invasive species can also modify soil properties benefiting other plants and soil biota (Ehrenfeld 2003 ; Lee et al 2012 ; Tun et al 2020 ). Invasive Pinus contorta have been proven to enrich the soil with lignin, P, Mg, and Mn (Ågren and Knecht 2001 ; Ehrenfeld 2003 ).…”